Radar reflector



May 19, 1953 D. J. MGAULEY ET; AL

RADAR REFLECTOR Filed March 24, 1950 Inventors.-

torneys.

Patented May 19, 1953 UNITED STATES PAT E'N'l ore-ice;

RADAR." BrE-FLEGEOR David J. McAuley and Harold. R c ards, London, and Edward W. Clark Lower Sydenham, London, England; assignors to- Suchy Holdings Limited, London, England; a-British company AnnlicationMarchfll, er a eNc- 151, 1 In Great Britain March 2 8 19 49;

4Glaims. 1

This inventionrelates to reflectors for use with radar ranging and detecting apparatus, and of the type employing three reflecting planes mutually at right angles. Such reflectors are usually termed corner reflectors and will be so called in this specification. The invention has for its object to provide an improved form of corner reflector which is satisfactory in operation and which, can be readily collapsed for transit or erected for use.

According to the present invention there is provided. a radar corner reflector comprising a plurality of panels of fiexible reflecting material supported by a collapsible framework so as to lie in three mutually perpendicular planes, at least those panels lying in two of said planes being secured along the whole of their periphery to relatively inflexible members forming part of said framework.

The invention also comprises. a radar corner reflector comprising a central supporting post to which are pivoted four arms and upon which slides a sleeve member or the like, four struts pivoted each at one end to the sleeve and at the other to the free end of one of; the arms, and four triangular panels offlexible reflecting material secured each with one side adjacent the central post, one side adjacent one of the four arms and one side adjacent the strut pivoted to that one Ofthe fourarms,

One embodiment of'the invention will now be described, by way of example, in which the corner reflector is oflight weight and can be 001- lapsed' into. a relatively small space for transit. The embodiment will be described with reference, to the, accompanying; drawings in. which:

Figure 1 is a perspective view of'the reflector erected for use, whilst a Figure 2 is a view of the, framework alone in-a semi-collapsed condition, the panels ofreflecting material not being shown for thesake of clarity.

Eigure 3; shows a detail view in side elevation of the; lower end of the reflector,-

Figure 4. shows a similar. view of; the upper end of the reflector, whilst Figure 5 shows a detail view in side elevation of thejunction between: a. strut and arm: ofrthe framework;

The reflector comprises a central post In of a lightweight metal alloy to which is attached, by means of a split pin I l passing through the post ID, a small cruciform support block l2 (see Figure 3). Pivoted to the block 12 by rivets l3 are four arms M which are of lightweight channel section, and the axes of the rivets l3 are arranged Zr so that the area Hi can pivot outwardlyat right angles to each other;

Slidable along the post H} is a sleeve member [5; which for convenience can be of the same shape as the support block l2, and towhieh are pivoted four struts I 6 by means of rivets 9-- (see Figure l). The strutslE are also of lightweight channel section material and each is pivoted at its outer end to the free; end of one of the arms It bymeans of adisc [8 to which the arm l4 and strut |6- are secured by-rivets 19 (see Figure 5). The arms [4' are allofthe samelength, asare all the struts l6, and the arms It andthe struts 18 are given suchrelative lengths that when the sleeve [5 is positioned tobring the struts 16 at right angles to the-post ID, the latter together with the arms I l and the struts lei-erming four frames, each substantially" the shape ofsa right-angled isosceles triangle, with the arms M curved slightly inwards at their-centre asshown in Figure 1;,

Four triangular panels H of lightweight; flexible conductingmaterial are secured inthe frames thus formed. A verysuitable-material for this purpose is an open mesh nylonnet rendered conductive by the process described in British patentspecification- No. 572,071. The panels I-'lare hemmed along those edges which are secured to the struts l6- and the arms E4, the struts it and the arms M being-inserted in the hems; w-h-ilst'the panels I? are secured to the post l-O bymeansofa tube z ii of fabric surroundingthe post lathe panels [7 being-sewn to'the tube 20;

When the framework is openedv out, as shown in Figure 1', the panels ll-lie intwo intersecting planes at right angles; inorder to completethe reflector it isnecessary'toprovide a reflecting surface'ina third plane at right angles to both the others. This-third reflectingsurface is pro.- vided by means of a squarepanel ni, 0f the same material 'asthe others, attached at its corners to the discs lB-at-thejoints betweenthearms 14; and thestruts It, the post B passing through an opening in the centre ofthe square. A fine steel or like' wire 25 passes round these joints throughthe holes 22* i-nthediscs -19 and is passed through ahemround" the edgeof the' square panel 2! to provide support for these edges.

The panels I1 and 2| are provided at their corners where they are attached to the supporting framework with small reinforcing pieces 23 of a suitable fabric material.

In use, to erect the reflector it is necessary only to draw the sleeve member 15 up the post 10;

thereby the struts [6 are pivoted outwardly, so as to tension both the triangular panels I! and the square panel 2|. The sleeve I is held in this position by means of a catch 24 in the post (see Figure 4), which is manually depressed against spring pressure to allow the sleeve member to ride over it.

For the satisfactory operation of a reflector of the type described it is essential that the reflector planes should be maintained accurately at right angles. With the, construction described the triangular panels I! are so maintained in use, since these will generally be in the vertical plane, with no tendency to sag out of that plane. In the case of the square panel 2|, however, this will usually be horizontal and being of large area may tend to sag at its centre."'

To check this tendency, the square panel 2| is attached at its centre to the post I!) by means of a pair of rubber washers 25 between which the panel 2| is clamped, the washers 25 surrounding and being frictionally secured to the post It as shown in Figure 4.

It may be stated, by way of example, that a reflector has been made having the above- 'described construction, in which the distance apart of the support block l2 and the sleeve member [5 was just over three feet, and the lengths of an arm M and a strut it were approximately four and one half feet and just over three feet respectively. The complete framework without the reflecting panels weighed approximately twenty ounces.

Reflectors according to the present invention have the normally-vertical panels of reflecting material supported throughout their peripheral length along two edges by a strut and arm respectively which are embraced by a, hem and along the third edge by attachment to the tube surrounding the central post. The panels can thus be retained substantially in a predetermined plane. The square or normally horizontal panel is similarly retained in a desired plane by means of the wire passing through its hemmed edge and the central rubber washers.

We claim:

1. A radar corner reflector comprising in combination a central supporting post, four arms pivoted each at one end to said post, a sleeve member slidably mounted on said post, four struts each pivotally secured at one end to that end of one of said arms not pivoted to said post and pivotally secured at their other end tosaid sleeve member, means for securing said sleeve member in a position on said post at which said four struts all lie in a plane, and four panels of flexible reflecting material each secured with one side adjacent the central post, one side adjacent one of the four arms and the other side adjacent that strut which is pivotally secured to the latter one of said arms.

2. In a radar corner reflector, a main post; a sleeve member slidable on said post; fixing means for selectively securing said sleeve member in a predetermined position on said post; 'four reflecting-material supporting frames uniformly angularly spaced around said post, said frames each comprising two longitudinal relatively inflexible members linked together at their one ends and secured by their other ends to said post and said sleeve member respectively; a tube of flexible material closely surrounding said post; four panels of flexible radar-reflecting material whose size corresponds to the space enclosed by a frame and said post with said sleeve member in said predetermined position, one edge of each of said panels being secured along its length to said tube and the other edges of said panels being hemmed, the hemmed edges of said panels enclosing said frames.

3. A radar corner reflector comprising in combination a central supporting post, four arms pivoted each at one end to said post, a sleeve member slidably mounted on said post, four struts each pivotally secured at one end to that end of one of said" arms not pivoted to said post and pivotally secured at their other end to said sleeve member, means for securing said sleeve member in a position on said post at which said four struts all lie in a plane, a tube of textile material secured closely around said central post, four triangular panels of flexible radar reflecting material, one edge of each of said panels being secured throughout the length of the edge to said tube of textile material and the other two edges of said panels being hemmed, the hemmed edges of said panels embracing one of said four arms and one of said four struts, and a further panel of flexible radar reflecting material suspended between the four junctions of said arms and struts in a plane to which said central post is perpendicular.

4. In a radar corner reflector, a tubular metal member; a further member slidable on said tubular member; catch means for securing said further member against sliding movement when desired in a predetermined position on said tubular member; four collapsible supporting frames secured to said post at equi-angular spacing therearound, said frames being connected to said further member whereby said frames are collapsed against said tubular member by movement of said further member from said predetermined position; a plurality of panels of flexible metallised fabric each supported along their edges by one of said frames and by said tubular member; and a further panel of flexible metallised fabric supported by said frames in a plane perpendicular to the longitudinal axis of said tubular member.

DAVID J. McAULEY. HAROLD E. G. RICHARDS. EDWARD W. CLARK.

References Cited in the file of this patent UNITED STATES PATENTS Date 

